Problem statement: Computer being indispensable in our daily lives came into use in all fields of education. Use of computer for education activities became mandatory. This research is an experimental research performed by use of computer in science and technology and is important in terms of serving science education. General purpose of this research is to reveal the effect of computer-assisted teaching practice for subject of heat and temperature in primary school grade 5, science and technology lesson on success attitudes. The answer of this question was sought: does computer-assisted teaching practice prepared for the subject of "heat-temperature" of primary school grade 5, science and technology have effect on success of students, attitudes towards science and technology and attitudes towards computer compared to traditional teaching? Approach: Pretest-Posttest Control Group Design was used. According to pre-test results applied in the beginning of research two equivalent classes were determined. While course was instructed by computer-assisted teaching in one class, course was instructed based on constructivist approach in the other class. 5th grade students who studied at a private primary school in the city centre of Antalya in spring term of 2009-2010 education years comprised the sampling of research. Three different assessment tools which were comprised of Heat and Temperature Subject Achievement Test, Science and Technology Lesson Attitude Scale and Computer Attitude Scale were used. Independent and matched t-test and definitional statistical methods were used to analyze the data. Results: Computer assisted teaching was observed to increase student success, it was noted that there was no change in students' attitude towards science and technology lesson and towards computer. This result is the quality of supporting many studies. It has emphasized in many studies that computer-assisted teaching has negative effects. Conclusion/Recommendations: Considering the findings, it was determined that attitudes of students towards computer, science and technology did not change. If we regard that attitude emerges as a result of reactions of individuals to objects in consequence of life and experiences, conducting such studies more comprehensive and long-term may be more effective. Computer-assisted teaching increased academic success of students. We can state following recommendations: computer-assisted teaching can be performed at all grades of primary school in science and technology classes, science and technology teachers can be trained in computer-assisted teaching and physical conditions of school can be designed as to allow computerassisted teaching. Findings of this study will contribute to choose teaching methods proper and effective for developing studies of computer-assisted teaching in the future.